Pressure actuated fuel injector



March 19, 1963 c. H. MAY

PRESSURE ACTUATED FUEL INJECTOR Filed 'Aug. 17, 1960 I I I ilnitehi rates Patent 3,081,758 PRESSURE ACTUATED FUEL INJECTOR Claude H. May, Racine, Wis, assignor to Walker Manufacturing Company, Racine, Wis, a corporation of Delaware Filed Aug. 17, 1960, Ser. No. 50,286 5 Claims. or. 123-139 This invention relates generally to internal combustion engines and more particularly to a fuel injector for an internal combustion engine.

Conventional fuel injectors used on internal combustion engines of, for example, the type used as prime movers for motor vehicles, characteristically have a plurality of relatively moving components that are required to be dimensionally accurate within relatively close tolerances. Such dimensional requirements increase the manufacturing cost of the injectors and the susceptibility thereof to failure due to wear. Also, such known injectors generally require relatively complex actuating and control linkages which inherently are dimcult to maintain in adjustment and in good working order.

The present invention is directed to a novel fuel injector wherein the relatively moving parts do not have critical dimensions and wherein complex control or actuating linkages are obviated. The fuel injector injects a metered quantity of fuel into the combustion chamber of the internal combustion engine, injection being timed to take place near the end of the compression stroke so as to insure adequate mixing of the fuel and air prior to ignition thereof by, for example, a'timed spark, a glow plug or an incandescent wire, preferably incorporated centrally of the fuel injector.

More particularly, a fuel injector in accordance with the present invention comprises a variable-volume pump that meters and pumps a quantity of fuel into the combustion chamber of the internal combustion engine. The fuel injector is activated by engine compression, the volume of the pump chamber being controlled by the effective pressure of the fuel supplied to the fuel injector. The fuel is discharged from the injector by a diflferential pressure responsive discharge valve.

Accordingly, one object of the present invention is an improved fuel injector for an internal combustion engine.

Another object is an improved fuel injector having relatively few moving parts.

Another object is a fuel injector wherein the moving parts do not require close dimensional accuracy Another object is a fuel injector that is excited and energized by engine compression.

Another object is a fuel injector adapted to be inserted in the spark plug aperture of a conventional internal combustion engine.

Another object is a fuel injector wherein the quantity of fuel injected on each operating cycle of the engine is determined by the upstream pressure of the fuel.

Other objects and advantages of the present invent-ion will become apparent from the following specification, wherein reference is made to the drawings, in which:

FIGURE 1 is a sectional side elevation of a fuel injector in accordance with an exemplary embodiment of the present invention; and

FIG. 2 is a fragmentary cross-sectional view taken substantially along the line 2--2 of FIGURE 1.

In accordance wit-h an exemplary embodiment of the present invention, a fuel injector comprises a cylindrical housing 12 having a threaded lower end portion 14 for acceptance in, for example, a spark plug aperture 15 in a cylinder head 16 of a conventional internal combustion engine (not shown). The housing 12 has a flange portion 17 extending radially outwardly from the lower end portion 14 and an axially upwardly extending portion ice 18 of relatively larger diameter than the lower end portion 14. The upper end portion 18 of the housing 12 has an annular groove .20 on an inner peripheral surface 22 thereof for the acceptance of a retaining ring 24. The upper end portion 18 of the housing 12 also has a plurality of circumferentially spaced notches 26 for the acceptance of a suitable tool (not shown) to facilitate advancement of the fuel injector 10 into the spark plug aperture 15 of the cylinder head 16.

A tubular sleeve 40 extends axially and centrally of the housing 12 for the acceptance and support of a spark plug 42. The spark plug 42 comprises a tubular metallic housing '43, a ceramic insulator 44 and a center electrode 45. Suitable terminals 46 and 47 are provided for electrical connection of the spark plug 42 to a source of electrical energy.

The sleeve 41} has an externally threaded lower end portion 48 that is engageable in a suitably threaded bore 49 in a sleeve housing 50. A lower end 52 of the sleeve housing 50 has a radia1 flange 54 with a counterbore 56 therein for the seating of an annular disc type discharge valve 60. The discharge valve 69 comprises a dished or Belleville washer having inner and outer peripheral edge surfaces 61 and 62 that are self-biased against the seat 56 on the sleeve 40 and a radial flange '63 of a valve retainer 64. The valve retainer 64 has a threaded upper end portion '65 engageable with complementary internal threads 66 on the lower end 48 of the sleeve 40. The valve retainer 64 has a central bore 68 for the acceptance of the spark plug 42.

The sleeve 40 has a plurality of circumferentially spaced axially extending slots 70 adapted to be radially aligned with complementary circumferentially spaced axially extending slots 71 on the inner periphery of the sleeve housing 50 for the passage of fuel downwardly between the sleeve housing 50 and sleeve 40, in a manner to be described.

The sleeve housing 50 has a radially outwardly extending flange 72 with an annular recess 73in an upper end face 74 thereof for the acceptance of a resilient sealing ring 75, for example, a conventional O-ring. It is to be noted that the end face 74 has a downwardly divergent conical cross-section to provide for axial movement of an annular disc type operating spring 80.

The spring is of dished cross section, for example, a Belleville washer, having a radially inner portion 82 that is positioned and retained axially of the plunger sleeve 50 by an annular inner spring retainer 90. The inner spring retainer has a plurality of axially downwardly extending ribs 92 on a lower end face 94 thereof that engage the inner end 82 of the spring 80 thereby biasing the spring Stl against the O-ring 75 in the annular groove 73 A radially outer edge portion 96 of the spring 80 is biased against a radially outwardly divergent upper end face 98 on the radially extending flange portion 17 of the housing 12. An outer spring retainer 16% has an annular groove 102 in a lower end face 104 thereof. for the acceptance of a sealing ring 106, for example, a conventional O-ring, thereby to effect a fluid seal with the radially outer portion 96 of the spring 86. The outer spring retainer has an annular groove in an outer peripheral surface 112 thereof for the acceptance of a sealing ring 114-, for example, a conventional O-ring. The outer spring retainer 100 is positioned axially of the housing 12 by the retainer ring 24.

The outer spring retainer 160 has a radially inwardly extending flange 120, a lower end face 121 of which serves as a stop or index position for a radial projection 122 on the spring retainer 90, for a reason to be discussed.

The flange has an annular recess 123 thereon for the positioning and seating of an annular dished disetype fuel inlet valve 124, for example, a Belleville washer. A sealing ring 125, for example an O-ring, has a slot 128 therein for the acceptance of an inner peripheral edge 130 of the valve 124. The sealing ring 126 is biased downwardly against an upper end face 132 of the inner spring retainer 90 by a valve spacer 149 that is interposed between the spring retainer 90 and an inner nut 150.

The inner nut 150 is suitably threaded so as to be engageable with the threaded upper end portion of the sleeve 40. The inner nut 150 has an upwardly convergent lower end face 152 terminating in a downwardly extending annular flange 154 for the positioning and retention of a resilient fuel intake manifold 160 which is made from, for example, neoprene rubber. Thus, relative movement between the sleeve 40 and its appended structure, and the outer housing 12, is accommodated by flexure of the resilient fuel intake manifold 16th.

The fuel intake manifold 160 has a pair of upwardly extending and opening nipples 162 and 164 for the acceptance of a pair of fuel inlet conduits 166 and 168, respectively. The manifold 160 has a pair of annular beads 170- and 172 on the outer and inner periphery thereof, the inner bead 172 being compressed between the nut 150 and the spacer 140 to effect a fluid seal therebetween. The outer bead 170 is compressed between an outer nut 180, having an upwardly divergent lower end face .182 and a downwardly extending flange 184 for the acceptance of the bead 170, and an upper end face 185 on the flange 129* of the spring retainer 100-. The nut 180 has a threaded portion 186 so as to be acceptable in a complementary threaded portion 188 of the outer spring retainer 100.

It is to be noted that the operating spring 80 normally biases the sleeve 40 and all the components appended thereto upwardly, which movement, in operation, is augmented by compression pressure on the lower end face of the sleeve 40, until the radial projection 122 thereon engages the lower end face 121 on the flange 120 of the outer spring retainer 100. This condition obtains at the end of the compression stroke to terminate fuel injection. From the termination of fuel injection until the piston (not shown) of the engine is in the last stages of its power stroke or at the beginning of the exhaust stroke, a pump chamber 200 defined by the volume between the inlet valve 124 and the discharge valve 60 is at a minimum volume. At this time, compression pressure on the sleeve 40* is relieved and fuel pressure in the pump chamber 209 drops below the fuel pressure in the fuel supply lines 166 and 168 because fuel pressure in the manifold 16% and the inherent bias of the inlet valve 124 is now effective to move the sleeve 40 downwardly, enlarging the pump chamber 200 an incremental amount. At this point the inlet valve 124 opens, allowing fuel to enter the pump chamber 200' whereupon the operating spring 80 is deflected downwardly and the central member 46 moves downwardly into the combustion chamber an amount such that the force due to fuel pressure in the pump chamber 200 and effective on the main spring 80 exactly balances the inherent spring force thereof. Thus, a relatively high fuel pressure in the manifold 160 results in greater downward deflection of the sleeve 40,

I increasing the volume of the chamber 209 and therefore exerted on the sleeve 40 augmenting the bias of the spring 8%} and tending to elevate the sleeve 4% and increase the pressure of the fuel trapped in the pump chamber to a pressure higher than the pressure in the engine combustion chamber.

The fuel pressure in the pump chamber 200 is communicated to the discharge valve through the fuel discharge passageways and 71.

When the pressure differential across the discharge valve 6% reaches a predetermined pressure, as preset by the spring loading of discharge valve" 60, the discharge valve 60 opens around its outer periphery 62 effecting injection of fuel into the engine combustion chamber where it is admixed with air and ignited by the centrally disposed spark plug 42.

During injection, the sleeve 40 moves upwardly, as seen in the drawings, until it is stopped by engagement of the projection 122 with the stop 12 1, the discharge valve 60 closing when the fuel pressure in the pump chamber 200 drops below a predetermined pressure.

As the expansion stroke nears completion and the exhaust stroke begins, fuel pressure in the pump chamber 200 drops sufficiently for the inlet valve 124 to open to refill the chamber 200.

Although in the above described preferred construction the operating spring normally biases the sleeve 49 and appended components upwardly against the stop 121, the fuel injector 10 may be so constructed that the spring 80 normally biases the sleeve 40 downwardly into the combustion chamber. Also, with appropriate seals and an externally movable and controllable stop, the stroke of the fuel injector 10 and the fuel flow may be regulated mechanically. Further, with an additional metering spring which has the proper load deflection and area characteristics, supply fuel pressure can be utilized to control the stroke of the unit as well as meter the proper quantity of fuel.

It is to be noted that the pre-set of the discharge valve 60 controls the timing of injection so that fuel may be injected at any time during the compression stroke.

From the foregoing description, it should be apparent that the fuel injector of the present invention has a minimum of critical dimensions requiring honing or grinding. For example, a fluid seal is effected between the manifold and the outer retainer 100 and valve spacer 149 by the resilient beads and 172 on the manifold 60. A fluid seal is maintained between the relatively moving sleeve housing 50 and outer spring retainer 100 by the annular seals 106 and 75. The inlet valve 124 is sealed with respect to the inner spring retainer 90 by the sealing ring 126 thereby eliminating critical dimensions on the inlet valve 124.

The chamber 200 which may be described as an elastically deformable chamber is made up ofcomponents that are resiliently sealed with respect to one another by the inherent bias of the rubber or spring materials employed thereby eliminating the sliding sealing fit inherent in heretofore known fuel injectors.

It is to be understood that the specific construction of the improved fuel injector herein disclosed and described is presented for the purpose of explanation and illustration and is not intended to indicate limits of the invention, the scope of which is defined by the following claims.

What is claimed is:

1. A compression excited fuel injectorfor an internal combustion engine having a combustion chamber with a working piston therein, said injector comprising a housing, a plunger movable with respect to said housing, a fuel intake manifold sealably connected to said housing and said plunger and extending therebetween, an intake valve extending between and normally seated against said housing and said plunger, a discharge valve extending between and normally seated against said housing and said plungensa-id intake and discharge valves in conjunction with said housing and plunger defining a variable displacement pump chamber, and means for normally biasing said plunger to an initial position witlrrespect to said housing thereby to define a minimum volume for said pump chamber, said intake valve being openable in response to a predetermined fuel pressure in said manifold to admit fuel into said pump chamber to increase the volume thereof relative to said minimum, said discharge valve being openable upon movement or" said plunger towards said initial position as the working piston in the engine combustion chamber moves on a cornp'ession stroke.

2. A compression excited fuel injector for an internal combustion engine having a combustion chamber with a Working piston therein, said injector comprising a gen erally tubular housing, a plunger disposed centrally of said housing and movable axially thereof, a fuel intake nanifold sealably connected to said housing and said plunger and extending therebetween, an intake valve extending between and normally seated against said housing and said plunger, a discharge valve extending between and normally seated against said housing and said plunger, said intake and discharge valves defining a variable displacement pump chamber, and means for normally biasing said plunger to an initial position with respect to said housing thereby to define a minimum volume for said pump chamber, said intake valve being openable in response to a predetermined fuel pressure in said manifold to admit fuel into said pump chamber to increase the volume thereof relative to said minimum volume, said discharge valve being openable upon movement of said plunger towards said initial position as the working piston in the engine combustion chamber moves on a compression stroke.

3. A compression excited fuel injector for an internal combustion engine having a combustion chamber with a working piston therein, said injector comprising a generally tubular housing, a generally cylindrical plunger disposed centrally of said housing and movable axially thereof, a generally annular fuel intake manifold having an inner peripheral edge sealably connected to said plunger and an outer peripheral edge sealably connected to said housing, an annular dished intake valve extending between and normally seated against said housing and said plunger, an annular dished discharge valve extending between and normally seated against said housing and said plunger, said intake and discharge valves defining a variable displacement pump chamber, and means for-normally biasing said plunger against a stop on said housing thereby to define a minimum volume for said pump chamber, said intake valve being openable in response to a predetermined fuel pressure in said manifold to admit fuel into said pump chamber to move said plunger away from said stop and to increase the volume of said chamber relative to said minimum volume, said discharge valve being openable upon movement of said d plunger towards said stop as engine combustion chamber stroke.

4. A compression excited fuel injector for an internal combustion engine having a combustion chamber with a working piston therein, said injector comprising a generally tubular housing, an annular plunger disposed centrally of said housing and movable axially thereof, a generally annular fuel intake manifold having an inner peripheral edge sealably connected to said plunger and an outer peripheral edge sealably connected to said. housing, an annular dished intake valve extending between and normally seated against said housing and said plunger, an annular dished discharge valve extending between and normally seated against said housing and said plunger, said intake and discharge valves defining a variable displacement pump chamber, an annular operating spring for normally biasing said plunger against a stop on said housing thereby to define a minimum volume for said pump chamber, said intake valve being openable in response to a predetermined fuel pressure in said manifold to admit fuel into said pump chamber to move said plunger away from said stop and to increase the volume of said chamber relative to said minimum volume, said discharge valve being openable upon movement of said plunger towards said stop as the working piston in the engine combustion chamber moves on a compression stroke, and ig ition means disposed centrally of said plunger and movable therewith, said ignition means extending into the combustion chamber of the engine to ignite the fuel subsequent to discharge thereof through said discharge valve.

5. A fuel injector for an internal combustion engine having a combustion chamber, said injector comprising a housing, a plunger movable with respect to said housing, a fuel intake manifold sealably engaging said housing and said plunger, an intake valve sealably engaged with said housing and said plunger, a discharge valve sealably engaged with said housing and said plunger, said intake and discharge valves in conjunction with said housing and plunger defining a variable displacement pump chamber, and means for defining a minimum volume for said pump chamber, said intake valve being openable in response to a predetermined fuel pressure in said manifold to admit fuel into said pump chamber, said discharge valve being openable upon the occurrence of a predetermined pressure diiierential between said pump chamber and the combustion chamber of the engine to inject fuel into the combustion chamber.

the working piston in the moves on a compression No references cited. 

1. A COMPRESSION EXCITED FUEL INJECTOR FOR AN INTERNAL COMBUSTION ENGINE HAVING A COMBUSTION CHAMBER WITH A WORKING PISTON THEREIN, SAID INJECTOR COMPRISING A HOUSING, A PLUNGER MOVABLE WITH RESPECT TO SAID HOUSING, A FUEL INTAKE MANIFOLD SEALABLY CONNECTED TO SAID HOUSING AND SAID PLUNGER AND EXTENDING THEREBETWEEN, AN INTAKE VALVE EXTENDING BETWEEN AND NORMALLY SEATED AGAINST SAID HOUSING AND SAID PLUNGER, A DISCHARGE VALVE EXTENDING BETWEEN AND NORMALLY SEATED AGAINST SAID HOUSING AND SAID PLUNGER, SAID INTAKE AND DISCHARGE VALVES IN CONJUNCTION WITH SAID HOUSING AND PLUNGER DEFINING A VARIABLE DISPLACEMENT PUMP CHAMBER, AND MEANS FOR NORMALLY BIASING SAID PLUNGER TO AN INITIAL POSITION WITH RESPECT TO SAID HOUSING THEREBY TO DEFINE A MINIMUM VOLUME FOR SAID PUMP CHAMBER, SAID INTAKE VALVE BEING OPERABLE IN RESPONSE TO A PREDETERMINED FUEL PRESSURE IN SAID MANIFOLD TO ADMIT FUEL INTO SAID PUMP CHAMBER TO INCREASE THE VOLUME THEREOF RELATIVE TO SAID MINIMUM, SAID DISCHARGE VALVE BEING OPERABLE UPON MOVEMENT OF SAID PLUNGER TOWARDS SAID INITIAL POSITION AS THE WORKING PISTON IN THE ENGINE COMBUSTION CHAMBER MOVES ON A COMPRESSION STROKE. 